1. Field of the Invention
The present invention relates to a gelatin product having improved properties of wettability and dispersibility in aqueous liquids irrespective of the temperature and having substantially higher hot-state dissolving speeds irrespective of the concentration as a result of a surface treatment which consists of film formation on gelatin particles by means of a hydrolyzed gelatin.
It is known that practically all applications of gelatins require preliminary dissolution of these latter in an aqueous liquid. This explains the importance attached to its properties of wettability, dispersibility and solubility.
2. Description of the Prior Art
In the present state of the art, three modes of operation are in common use:
(a) swelling of the gelatin grains in the cold liquid followed by melting of the swollen grains in the hot state; PA1 (b) direct dissolution of the gelatin in hot liquids; PA1 (c) swelling of the gelatin grains in a minimum quantity of cold water followed by melting of these swollen grains in a hot liquid. PA1 (a) Agitation of the basic gelatin to be film-coated: PA1 (b) Dissolving of the hydrolyzed gelatin at a concentration of 0.1 to 50% by weight in an aqueous liquid at a temperature within the range of 20.degree. to 80.degree. C. PA1 (c) Wetting of the basic gelatin with agitation by the hydrolyzed gelatin solution by sprinkling, immersion or spraying within the apparatus chosen for producing agitation so as to ensure that the quantity of hydrolyzed gelatin added is 0.1 to 10% by weight of dry extract with respect to the mass of basic gelatin to be film-coated as expressed by weight of dry extract. PA1 (d) Drying of the film-coated gelatin with hot air at a temperature of 30.degree. to 80.degree. C., either within the film-forming apparatus (in particular if this apparatus is a pelletizing drum or a fluidized air bed device) or in a suitable drying apparatus in the case of a mixer or another equipment unit which does not permit a drying operation. PA1 1. A COURTS, Biochem. J, 1955, 59 382 "Specificity of enzymes towards gelatin" PA1 2. E. D. LEVIN, C. L. MURATOVA, M. STEPANOV, Khim. Pirodn. Soedn. Akad. Nauk. USSR, 1961, 208 "Hydrolysis of gelatin by gelitanase". PA1 3. O. S. TSIPEROVICH, I. F. MISHUNIN, Ukr. Biokhim. ZH, 1970, 42 367 "Hydrolysis of gelatin by a streptomyces griseus enzyme". PA1 4. A. GANSEL, P.S.A. Journ. Section B, p. 82 (Oct. 1952) "Study of rate hydrolysis of gelatin". PA1 5. Patent DU PONT DE NEMOURS, 1971, FR 2 099 777, "Preparation of hydrolyzed gelatins prior to chemical modification". PA1 either to perform individual film-coating of grains of the basic gelatin without any significant modification of the particle-size curve, of the apparent volume and of the apparent density; PA1 or on the contrary to facilitate agglomeration of the individually film-coated grains with each other, the result thereby achieved being: PA1 or to obtain any intermediate result between the two preceding results.
These three techniques present problems of wettability and dispersibility both in the cold state and in the hot state, the more so as the particle size of the gelatin is smaller.
Moreover, and for this reason, the method of direct dissolution usually makes it necessary in the case of the usual concentrations to adopt an initial step of dispersion of the product by very rapid agitation. This results in a substantial inclusion of air and formation of microbubbles which take a longer time and are more difficult to remove as the concentration of gelatin and therefore the viscosity of the solution are higher.
The methods which involve swelling in the cold state are not subject to the drawbacks mentioned in the preceding paragraph but are considered excessively time-consuming by an ever-increasing number of users.
For the reasons given in the foregoing, several attempts have been made to overcome these disadvantages such as spray-atomization of gelatins on a number of different supports such as sugars, maltodextrins or starches.
These formulae have produced a few advantages in some instances, in particular in regard to dissolving speed but have failed to improve the dispersibility by reason of their very small particle size which is inherent in atomized powders.
Also worthy of mention is French Pat. No. 2,167,197 which describes a process for drying gelatin without passing through the gelled state in order to make it soluble in the cold state. The compositions mentioned contain only 1 to 50% by weight of gelatin and require the addition of 2 to 5 times their weight of solid ingredients in order to obtain satisfactory wettability and dispersibility in cold liquids.
Other attempts have been made to carry out coating of gelatin grains with various dispersion products such as lecithin, silicones or wetting agents.
Apart from the fact that they are always more costly than gelatin, these products are food additives having limited use.